The basic principle of the cone pump, or the screw pump is as old as Archimedes. In fact, these pumps are commonly referred to in the art as Archimedes Screw Pumps. Fundamentally, the screw pump consists of a tubular member containing a helically arranged elevator, so that when the device is inclined with its lower end in water and it is rotated about its longitudinal axis, water is lifted from stage to stage within the mechanism and, in many relatively inefficient arrangements, water can be lifted to heights of 10 or 20 feet in a single pass. While the pumps have much to be desired in terms of their efficiency they do constitute a useful means for lifting water in many types of situations, because they are of relatively simple construction. Maintenance is easy.
A variety of improvements have been devised and the pumps are currently relatively popular for such uses as moving sewage sludge from a collection pit to an elevated area. Their performance at intake and outlet is ragged. That is, there is a considerable amount of splashing of liquid and sludge which makes the operation considerably untidier than it need be. Shaft deflection and "screw to housing" clearance have reduced pump efficiency and limited pump lift height and capacity.
It is accordingly a basic object of this invention to provide an improved screw type pump, having improved intake, lift, and discharge features, so that it can relatively efficiently move liquids such as aqueous sewage sludge through an incline as much as 45.degree. to 50.degree., or more, against a head of 20 to 30 feet.
Other objects and advantages of the invention will in part be obvious and in part appear hereinafter.